In recent years, advances in technology, as well as ever evolving tastes in style, have led to substantial changes in the design of automobiles. One of the changes involves the power usage and complexity of the various electrical systems within automobiles, particularly alternative fuel vehicles, such as hybrid, electric, and fuel cell vehicles.
Many of the electrical components, including the electric motors used in such vehicles, receive electrical power from alternating current (AC) power supplies. However, the power sources (e.g., batteries) used in such applications provide only direct current (DC) power. Thus, devices known as “power inverters” are used to convert the DC power to AC power, which often utilize several of switches, or transistors, operated at various intervals to convert the DC power to AC power.
Additionally, such vehicles, particularly fuel cell vehicles, often use two separate voltage sources (e.g., a battery and a fuel cell) to power the electric motors that drive the wheels. “Power converters,” such as direct current-to-direct current (DC/DC) converters, are typically used to manage and transfer the power from the two voltage sources. Modern DC/DC converters often include transistors electrically interconnected by an inductor. By controlling the states of the various transistors, a desired average current can be impressed through the inductor and thus control the power flow between the two voltage sources.
The utilization of both a power inverter and a power converter greatly increases the complexity of the electrical system of the automobile. The additional components required for both types of devices also increase the overall cost and weight of the vehicle. Systems and methods have been developed for operating a motor coupled to multiple power sources without a DC/DC converter while maximizing the performance of the motor by utilizing dual inverter electrical systems. In a dual inverter system, the voltage required to produce a commanded torque in the motor is provided by the two inverters. Therefore, numerous combinations of voltages can be generated to produce the required torque.
Accordingly, it is desirable to provide methods and systems for determining an optimal operating condition and combination of voltages that minimizes total power loss in the inverter system while maintaining the benefits of a dual inverter system. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.